[osg-users] When optimizing with LOD changes, should I change UV map resolutions?
Hello All, I have been trying to get my scenes to run faster, balancing my scene graphs using LOD. I use quite a bit of UV mapping in my models, and they can be fairly high res because I want them to look good up close. There are usually several instances of the same model in the scene, all pointing to the same scene graph. I was wondering about the best way to create LOD changes for them. I was going to cut out some polygons, but I was also thinking of cutting the resolution back on the UV maps. Is this valuable? On first assessment, it seems it would be, but then I realize that it might cause MORE of a memory usage, and the graphics card (or OSG) might be doing this kind of optimization anyway (dropping image map resolutions based on pixel size or whatever). What are your recommendations? -- Thanks for everything Rick Check us out at http://fringe-online.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] When optimizing with LOD changes, should I change UV map resolutions?
Hi Rick, The most efficient LOD's will be the ones created by specialist tools, or even a decent modeller. The aim of the lower level of details subgraphs would be to represent the subgraph with less of everything - less nodes, less separate state, less geometry, smaller textures, simpler shaders etc. The ideal would be collapsing down to a single osg::Geode/osg::Geometry and with a single osg::StateSet and a single Texture.Using a texture atlas is a good way to collapse separate textures down into a single texture. osgUtil::Optimizer has a texture atas builder that could help with this. Robert. On Thu, Jul 10, 2008 at 2:08 PM, [EMAIL PROTECTED] wrote: Hello All, I have been trying to get my scenes to run faster, balancing my scene graphs using LOD. I use quite a bit of UV mapping in my models, and they can be fairly high res because I want them to look good up close. There are usually several instances of the same model in the scene, all pointing to the same scene graph. I was wondering about the best way to create LOD changes for them. I was going to cut out some polygons, but I was also thinking of cutting the resolution back on the UV maps. Is this valuable? On first assessment, it seems it would be, but then I realize that it might cause MORE of a memory usage, and the graphics card (or OSG) might be doing this kind of optimization anyway (dropping image map resolutions based on pixel size or whatever). What are your recommendations? -- Thanks for everything Rick Check us out at http://fringe-online.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] When optimizing with LOD changes, should I change UV map resolutions?
Robert's comment regarding texture atlas usage in low-res LOD children is an excellent suggestion. Going further, your post begs the question: Do you suspect that texture memory usage is the bottleneck to your performance? One way to test this (if you haven't already done so) is to set the OSG environment variable to limit the maximum texture dimension to something ridiculously small. If your app runs faster with this setting, then texture memory usage might be causing performance problems, and you might need to address that in some way. You should keep in mind that most OpenGL device drivers are smart enough to page out large mipmap levels when they are not in use. Another thing to keep in mind is that a texture never needs to be larger than its max representation on-screen. For example, it's pointless to have a 2kx2k texture applied to an object that will never subtend more than 500x500 pixels. Hope that helps. -Paul _ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, July 10, 2008 7:09 AM To: OpenSceneGraph Users Subject: [osg-users] When optimizing with LOD changes,should I change UV map resolutions? Hello All, I have been trying to get my scenes to run faster, balancing my scene graphs using LOD. I use quite a bit of UV mapping in my models, and they can be fairly high res because I want them to look good up close. There are usually several instances of the same model in the scene, all pointing to the same scene graph. I was wondering about the best way to create LOD changes for them. I was going to cut out some polygons, but I was also thinking of cutting the resolution back on the UV maps. Is this valuable? On first assessment, it seems it would be, but then I realize that it might cause MORE of a memory usage, and the graphics card (or OSG) might be doing this kind of optimization anyway (dropping image map resolutions based on pixel size or whatever). What are your recommendations? -- Thanks for everything Rick Check us out at http://fringe-online.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] When optimizing with LOD changes, should I change UV map resolutions?
Wow, the ability to limit the maximum texture memory sounds like it would really help. What/where might I find that environment variable? -- Rick On Thu, Jul 10, 2008 at 11:26 AM, Paul Martz [EMAIL PROTECTED] wrote: Robert's comment regarding texture atlas usage in low-res LOD children is an excellent suggestion. Going further, your post begs the question: Do you suspect that texture memory usage is the bottleneck to your performance? One way to test this (if you haven't already done so) is to set the OSG environment variable to limit the maximum texture dimension to something ridiculously small. If your app runs faster with this setting, then texture memory usage might be causing performance problems, and you might need to address that in some way. You should keep in mind that most OpenGL device drivers are smart enough to page out large mipmap levels when they are not in use. Another thing to keep in mind is that a texture never needs to be larger than its max representation on-screen. For example, it's pointless to have a 2kx2k texture applied to an object that will never subtend more than 500x500 pixels. Hope that helps. -Paul -- *From:* [EMAIL PROTECTED] [mailto: [EMAIL PROTECTED] *On Behalf Of * [EMAIL PROTECTED] *Sent:* Thursday, July 10, 2008 7:09 AM *To:* OpenSceneGraph Users *Subject:* [osg-users] When optimizing with LOD changes,should I change UV map resolutions? Hello All, I have been trying to get my scenes to run faster, balancing my scene graphs using LOD. I use quite a bit of UV mapping in my models, and they can be fairly high res because I want them to look good up close. There are usually several instances of the same model in the scene, all pointing to the same scene graph. I was wondering about the best way to create LOD changes for them. I was going to cut out some polygons, but I was also thinking of cutting the resolution back on the UV maps. Is this valuable? On first assessment, it seems it would be, but then I realize that it might cause MORE of a memory usage, and the graphics card (or OSG) might be doing this kind of optimization anyway (dropping image map resolutions based on pixel size or whatever). What are your recommendations? -- Thanks for everything Rick Check us out at http://fringe-online.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- Rick Check us out at http://fringe-online.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] When optimizing with LOD changes, should I change UV map resolutions?
On Thu, Jul 10, 2008 at 5:13 PM, Rick Pingry [EMAIL PROTECTED] wrote: Wow, the ability to limit the maximum texture memory sounds like it would really help. What/where might I find that environment variable? You can list the env vars by doing: osgviewer --help-env One of the entries will be: OSG_MAX_TEXTURE_SIZE Set the maximum size of textures. So you do something like: set OSG_MAX_TEXTURE_SIZE=64 myapp mymodel.fmt Robert. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] When optimizing with LOD changes, should I change UV map resolutions?
The OSG Ref Man v2.2 (www.osgbooks.com) has a complete reference of OSG environment variables. The one you want is OSG_MAX_TEXTURE_SIZE. -Paul From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Rick Pingry Sent: Thursday, July 10, 2008 10:14 AM To: OpenSceneGraph Users Subject: Re: [osg-users] When optimizing with LOD changes,should I change UV map resolutions? Wow, the ability to limit the maximum texture memory sounds like it would really help. What/where might I find that environment variable? -- Rick On Thu, Jul 10, 2008 at 11:26 AM, Paul Martz [EMAIL PROTECTED] wrote: Robert's comment regarding texture atlas usage in low-res LOD children is an excellent suggestion. Going further, your post begs the question: Do you suspect that texture memory usage is the bottleneck to your performance? One way to test this (if you haven't already done so) is to set the OSG environment variable to limit the maximum texture dimension to something ridiculously small. If your app runs faster with this setting, then texture memory usage might be causing performance problems, and you might need to address that in some way. You should keep in mind that most OpenGL device drivers are smart enough to page out large mipmap levels when they are not in use. Another thing to keep in mind is that a texture never needs to be larger than its max representation on-screen. For example, it's pointless to have a 2kx2k texture applied to an object that will never subtend more than 500x500 pixels. Hope that helps. -Paul From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, July 10, 2008 7:09 AM To: OpenSceneGraph Users Subject: [osg-users] When optimizing with LOD changes,should I change UV map resolutions? Hello All, I have been trying to get my scenes to run faster, balancing my scene graphs using LOD. I use quite a bit of UV mapping in my models, and they can be fairly high res because I want them to look good up close. There are usually several instances of the same model in the scene, all pointing to the same scene graph. I was wondering about the best way to create LOD changes for them. I was going to cut out some polygons, but I was also thinking of cutting the resolution back on the UV maps. Is this valuable? On first assessment, it seems it would be, but then I realize that it might cause MORE of a memory usage, and the graphics card (or OSG) might be doing this kind of optimization anyway (dropping image map resolutions based on pixel size or whatever). What are your recommendations? -- Thanks for everything Rick Check us out at http://fringe-online.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- Rick Check us out at http://fringe-online.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
